Method and apparatus for validating stored system information

ABSTRACT

A system for converging fifth generation (5G) communication systems for supporting higher data rates beyond fourth generation (4G) systems with a technology for Internet of things (IoT) is provided. The communication method and system may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A terminal and base station are provided for performing beam failure detection and a recovery procedure using first and second configuration information for beam failure recovery (BFR) and if failure is detected, initiating a first random access (RA) procedure and if second configuration information is received while the first RA procedure is ongoing, terminating the first RA procedure and initiating a second RA procedure based on the second configuration information.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. §119(a) of an Indian patent application number 201831029682, filed onAug. 7, 2018, in the Indian Patent Office, the disclosure of which isincorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a system and a method for stored systeminformation (SI) validation and beam failure configuration update.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of fourth generation (4G) communication systems, efforts havebeen made to develop an improved fifth generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘beyond 4G network’ or a ‘post long term evolution(LTE) System’. The 5G wireless communication system is considered to beimplemented not only in lower frequency bands, but also in higherfrequency (mm Wave) bands, e.g., 10 GHz to 100 GHz bands, so as toaccomplish higher data rates. To mitigate propagation loss of the radiowaves and increase the transmission distance, beamforming, massivemultiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO),array antenna, analog beam forming, and large scale antenna techniquesare being considered in the design of the 5G wireless communicationsystem. In addition, in 5G communication systems, development for systemnetwork improvement is underway based on advanced small cells, cloudradio access networks (RANs), ultra-dense networks, device-to-device(D2D) communication, wireless backhaul, moving network, cooperativecommunication, coordinated multi-points (CoMP), reception-endinterference cancellation, and the like. In the 5G system, frequency andquadrature amplitude modulation (FQAM), which is a combination of hybridfrequency shift keying (FSK) and quadrature amplitude modulation (QAM),and sliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), filter bank multi-carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology, have also been developed.

In a similar regard, the Internet, which is a human centeredconnectivity network where humans generate and consume information, isnow evolving to the internet of things (IoT) where distributed entities,such as things, exchange and process information without humanintervention. The internet of everything (IoE), which is a combinationof IoT technology and big data processing technology through connectionwith a cloud server, has also emerged. As technology elements, such as“sensing technology,” “wired/wireless communication and networkinfrastructure,” “service interface technology,” and “securitytechnology” have been demanded for IoT implementation, a sensor network,a machine-to-machine (M2M) communication, machine-type communication(MTC), and so forth, have been recently researched. Such an IoTenvironment may provide intelligent Internet technology services thatcreate a new value to human life by collecting and analyzing datagenerated among connected things. In this case, IoT may be applied to avariety of fields including a smart home, smart building, smart city,smart car or connected cars, smart grid, health care, smart appliances,and advanced medical services through convergence and combinationbetween existing information technology (IT) and various industrialapplications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication, may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RAN as theabove-described big data processing technology may also be considered tobe an example of convergence between the 5G technology and the IoTtechnology.

In recent years several broadband wireless technologies have beendeveloped to meet the growing number of broadband subscribers and toprovide more and better applications and services such as these. Thesecond generation (2G) wireless communication system has been developedto provide voice services while ensuring the mobility of users. Thirdgeneration (3G) wireless communication system supports not only thevoice service, but also data service. The 4G wireless communicationsystem has been developed to provide high-speed data service. However,the 4G wireless communication system currently suffers from lack ofresources to meet the growing demand for high-speed data services.Therefore, the 5G wireless communication system is being developed tomeet the growing demand of various services with diverse requirements,e.g. high-speed data services, support ultra-reliability and low latencyapplications.

In addition, the 5G wireless communication system is expected to addressdifferent use cases having quite different requirements in terms of datarate, latency, reliability, mobility, etc. However, it is expected thatthe design of the air-interface of the 5G wireless communication systemwould be flexible enough to serve user equipments (UEs) having quitedifferent capabilities depending on the use case and market segment inwhich the UE caters service to the end customer. Example use cases the5G wireless communication system is expected to address includesenhanced mobile broadband (eMBB), massive Machine Type Communication(m-MTC), ultra-reliable low latency communication (URLL), etc. The eMBBrequirements like tens of Gbps data rate, low latency, high mobility soon, address the market segment representing the conventional wirelessbroadband subscribers needing internet connectivity everywhere, all thetime and on the go. The m-MTC requirements like very high connectiondensity, infrequent data transmission, very long battery life, lowmobility address so on, address the market segment representing theIoT/IoE envisioning connectivity of billions of devices. The URLLrequirements like very low latency, very high reliability and variablemobility so on, address the market segment representing the Industrialautomation application, vehicle-to-vehicle/vehicle-to-infrastructurecommunication that is foreseen as one of the enablers for autonomouscars.

In the 4G wireless communication system, an evolved node B (eNB) or basestation (BS) in cell broadcasts system information (SI). The SI isstructured into a master information block (MIB) and a set of systeminformation blocks (SIGs). The MIB consists of a system frame number(SFN), downlink system bandwidth (BW) and physical hybrid automaticrepeat request (ARQ) feedback indicator channel (PHICH) configuration.An example MIB is transmitted every 40 ms. It is repeated every 10 mswherein the first transmission occurs in subframe #0 when SFN mod 4equals zero. The MIB is transmitted on physical broadcast channel(PBCH). The SIB Type 1 (i.e., SIB1) carries cell identity, tracking areacode, cell barring information, value tag (common for all schedulingunits), and scheduling information of other SIBs. The SIB1 istransmitted every 80 ms in subframe #5 when SFN mod 8 equals zero. TheSIB1 is repeated in subframe #5 when SFN mod 2 equals zero. The SIB1 istransmitted on physical downlink shared channel (PDSCH). Other SIBs(i.e. SIB2 to SIB19) are transmitted in an SI message wherein schedulinginfo of these SIBs are indicated in SIB1.

The UE acquires the SI at cell selection, cell reselection, afterhandover completion, after entering evolved universal mobiletelecommunications system (UMTS) terrestrial radio access (E-UTRA) fromanother radio access technology (RAT), upon re-entering service area,upon receiving a notification (paging), and upon exceeding the maximumvalidity duration (3 hours). In a radio resource control (RRC) idlestate and inactive state, the UE needs to acquire MIB, SIB1, SIB2, SIB3,SIB4, SIBS, SIB6, SIB7 and SIB8 (depending on RAT supported), SIB17 (ifLTE-wireless local area network (WLAN) interworking (IWK) is supported),and SIB18 to SIB19 (if D2D is supported). In an RRC connected state, theUE needs to acquire MIB, SIB1, SIB2, SIB8 (depending on RAT supported),SIB17 (if LTE-WLAN IWK is supported), and SIB18 and SIB19 (if D2D issupported).

In the next generation wireless communication system (i.e., 5G), SI isdivided into the MIB and a number of SIBs where:

(1) the MIB is always transmitted on the broadcast channel (BCH) with aperiodicity of 80 ms and repetitions made within 80 ms and it includesparameters that are needed to acquire SIB1 from the cell. The firsttransmission of the MIB is scheduled in subframes defined by of radioframes for which the SFN mod 8=0, and repetitions are scheduled in otherradio frames according to the period of synchronization signal (SS)block (SSB);

(2) the SIB1 is transmitted on the downlink shared channel (DL-SCH) witha periodicity of 160 ms and variable transmission repetitionperiodicity. The default transmission repetition periodicity of SIB1 is20 ms, but the actual transmission repetition periodicity is up tonetwork implementation. For SSB and control resource set (CORESET)multiplexing pattern 1, SIB1 repetition transmission period is 20 ms.For SSB and CORESET multiplexing pattern 2/3, SIB1 transmissionrepetition period is the same as the SSB period. The SIB1 includesinformation regarding the availability and scheduling (e.g., mapping ofSIBs to SI message, periodicity, SI-window size) of other SIBs with anindication whether one or more SIBs are only provided on-demand and, inthat case, the configuration needed by the UE to perform the SI request.The SIB1 is also cell-specific SIB; and

(3) SIBs other than SIB1 are carried in System Information (SI)messages, which are transmitted on the DL-SCH. Only SIBs having the sameperiodicity can be mapped to the same SI message. Each SI message istransmitted within periodically occurring time domain windows (referredto as SI-windows with same length for all SI messages). Any SIB exceptSIM can be configured to be cell specific or area specific. The cellspecific SIB is applicable only within a cell that provides the SIBwhile the area specific SIB is applicable within an area referred to asSI area, which consists of one or several cells and is identified bysystemInformationAreaID.

In the 5G system, the UE acquires the SI acquisition upon cell selection(e.g., upon power on), cell-reselection, return from out of coverage,after reconfiguration with sync completion, after entering the networkfrom another RAT, upon receiving an indication that the systeminformation has changed, upon receiving a public warning system (PWS)notification; and/or whenever the UE does not have a valid version of astored SI.

The above information is presented as background information only, andto assist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages, and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea communication method and system for converging a fifth generation (5G)communication system for supporting higher data rates beyond a fourthgeneration (4G) system.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

User equipment (UE) stores the acquired system information (SI) from thecamped/serving cell. Due to UE mobility, camped/serving cell keepschanging and UE keeps storing SI acquired from each camped/serving cell.A version of the SI that the UE stored is no longer valid 3 hours afteracquisition. The UE may use a valid stored version of the SI except MIBand SIB1, e.g., after cell re-selection, upon return from out ofcoverage or after the reception of SI change indication. So UE is notrequired to store MIB of a camped/serving cell after the UE moves toanother cell. SIs other than SIB1 do not include any information toidentify the cell/PLMN/system information area to which those SIsbelong. So SIB1 contents needs to be stored. However storing SIB1 forevery camped/serving cell consumes a lot of memory. So UE needs todetermine which contents from SIB1 needs to stored. The systeminformation block 1 (SIB1) acquired from camped/serving cell includespublic land mobile network (PLMN) identity information listPLMN-IdentilyInfoList comprised of multiple PLMNs. Therefore, inaccordance with an aspect of the disclosure, a method is provided todetermine which PLMN from the PLAIN-IdentilyInfoList in the SIB1acquired from that cell are associated with stored SIBs acquired fromthat cell. The system information area is maintained per PLMN. If the UEuses any PLMN then this may lead to wrong usage of stored SI in anothercell.

Upon detecting the beam failure, random access (RA) procedure for beamfailure recovery (BFR) is initiated and is continued until it iscompleted. The BFR configuration provided by the base station can beupdated while the RA procedure for BFR is ongoing. For example, whileBFR recovery is being performed for primary secondary cell (PSCell), UEmay receive updated BFR configuration from primary (PCell). In a firstscenario, UE is configured with beam failure detection and BFRconfiguration. Contention free RA resources are provided for BFRrequest. UE detects beam failure and initiates RA Procedure for BFR.While the RA procedure for BFR is ongoing, UE receivesRRCReconfiguration including updated BFR configuration (contention freeRA resources for BFR request are updated). In this case, continuation ofRA procedure, will lead to usage of contention free BFR resources whichare no longer valid. This will result in interference and BFR will notbe successful. In a second scenario, UE is configured with beam failuredetection and BFR configuration (contention free RA resources are notprovided for BFR request). UE detects beam failure and initiates RAprocedure for BFR. While the RA procedure for BFR is ongoing, UEreceives RRCReconfiguration including BFR configuration (contention freeRA resources are provided). In this case, continuation of RA procedurewill lead to usage of only the contention based RA resources for BFReven when contention free RA resources are available. This will resultin delay in BFR.

In accordance with another aspect of the disclosure, a method by aterminal for determining system information validity is provided. Themethod includes acquiring a first SIB1 and other system informationbased on the first SIB1, storing at least part of the first SIB1 and theother system information, wherein the stored at least part of the firstSIB1 includes information on a PLMN identity and a value tag of thefirst SIB1, receiving a second SIB1 from a cell, and determining whetherthe stored at least part of the first SIB1 and the other systeminformation are valid for the cell based on whether information on aPLMN identity and a value tag of the second SIB1 are identical to thestored information on the PLMN identity and the stored value tag.

In accordance with another aspect of the disclosure, a terminal in acommunication system is provided. The terminal includes a transceiverand at least one processor coupled with the transceiver. The at leastone processor is configured to acquire a first SIB1 and other systeminformation based on the first SIB1, store at least part of the firstSIB 1 and the other system information, wherein the stored at least partof the first SIB1 includes information on a PLMN identity and a valuetag of the first SIB1, control the transceiver to receive a second SIB1from a cell, and determine whether the stored at least part of the firstSIB1 and the other system information are valid for the cell based onwhether information on a PLMN identity and a value tag of the secondSIB1 are identical to the stored information on the PLMN identity andthe stored value tag.

In accordance with another aspect of the disclosure, a method by aterminal for performing a beam failure detection and recovery procedureis provided. The method includes receiving, from a base station, firstconfiguration information for beam failure recovery (BFR) and if beamfailure is detected, initiating a first random access (RA) procedure forBFR based on the first configuration information, and if secondconfiguration information for BFR is received while the first RAprocedure is ongoing, terminating the first RA procedure and initiatinga second RA procedure for BFR based on the second configurationinformation.

In accordance with another aspect of the disclosure, a method by a basestation for performing a BFR procedure is provided. The method includestransmitting to a terminal first configuration information for BFR,transmitting to the terminal second configuration information for BFR,and receiving from the terminal a BFR request. If the secondconfiguration is transmitted while the terminal performs an RA procedurefor BFR based on the first configuration, the request is based on thesecond configuration.

In accordance with another aspect of the disclosure, a terminal in acommunication system is provided. The terminal includes a transceiverand at least one processor coupled with the transceiver. The at leastone processor is configured to control the transceiver to receive, froma base station, first configuration information for BFR and if beamfailure is detected, initiate a first RA procedure for BFR based on thefirst configuration information, and if second configuration informationfor BFR is received while the first RA procedure is ongoing, terminatethe first RA procedure and initiate a second RA procedure for BFR basedon the second configuration information.

In accordance with another aspect of the disclosure, a base station in acommunication system is provided. The base station includes atransceiver and at least one processor coupled with the transceiver. Theat least one processor is configured to control the transceiver totransmit to a terminal first configuration information for BFR, controlthe transceiver to transmit to the terminal second configurationinformation for BFR, and control the transceiver to receive from theterminal a BFR request. If the second configuration is transmitted whilethe terminal performs an RA procedure for BFR based on the firstconfiguration, the request is based on the second configuration.

The embodiments in the proposed disclosure provide methods to reduceinterference and delay during BFR. Additionally, the embodiments in theproposed disclosure provide methods to determine the PLMN to beassociated with stored SI so that UE can utilize this information tocorrectly determine whether stored SI acquired from a cell can beutilized in another cell upon cell selection (e.g., upon power on),cell-reselection, return from out of coverage, after reconfigurationwith sync completion, etc.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a flowchart that shows user equipment (UE) operations forvalidating stored system information (SI) according to an embodiment ofthe disclosure;

FIG. 2 is another flowchart that shows UE operations for validatingstored SI according to an embodiment of the disclosure;

FIG. 3 is another flowchart that shows UE operations for validatingstored SI according to an embodiment of the disclosure;

FIG. 4 is another flowchart that shows UE operations for validatingstored SI according to an embodiment of the disclosure;

FIG. 5 shows signaling flow between a UE and a next generation node B(gNB) according to an embodiment of the disclosure;

FIG. 6 is a flowchart that shows UE operations according to anembodiment of the disclosure;

FIG. 7 shows signaling flow between a UE and a gNB according to anembodiment of the disclosure;

FIG. 8 is another flowchart that shows UE operations according to anembodiment of the disclosure;

FIG. 9 shows another signaling flow between a UE and a gNB according toan embodiment of the disclosure;

FIG. 10 is another flowchart that shows UE operations according to anembodiment of the disclosure;

FIG. 11 is a block diagram of a terminal according to an embodiment ofthe disclosure; and

FIG. 12 is a block diagram of a base station according to an embodimentof the disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding, but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but are merely used to enable aclear and consistent understanding of the disclosure. Accordingly, itshould be apparent to those skilled in the art that the followingdescription of various embodiments of the disclosure is provided forillustration purpose only, and not for the purpose of limiting thedisclosure as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

By the term “substantially” it is meant that the recited characteristic,parameter, or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to those ofskill in the art, may occur in amounts that do not preclude the effectthe characteristic was intended to provide.

It is known to those skilled in the art that blocks of a flowchart (orsequence diagram) and a combination of flowcharts may be represented andexecuted by computer program instructions. These computer programinstructions may be loaded on a processor of a general purpose computer,special purpose computer, or programmable data processing equipment.When the loaded program instructions are executed by the processor, theycreate a means for carrying out functions described in the flowchart.Because the computer program instructions may be stored in a computerreadable memory that is usable in a specialized computer or aprogrammable data processing equipment, it is also possible to createarticles of manufacture that carry out functions described in theflowchart. Because the computer program instructions may be loaded on acomputer or a programmable data processing equipment, when executed asprocesses, they may carry out operations of functions described in theflowchart.

A block of a flowchart may correspond to a module, a segment, or a codecontaining one or more executable instructions implementing one or morelogical functions, or may correspond to a part thereof. In some cases,functions described by blocks may be executed in an order different fromthe listed order. For example, two blocks listed in sequence may beexecuted at the same time or executed in reverse order.

In this description, the words “unit”, “module” or the like may refer toa software component or hardware component, such as, for example, afield-programmable gate array (FPGA) or an application-specificintegrated circuit (ASIC) capable of carrying out a function or anoperation. However, a “unit”, or the like, is not limited to hardware orsoftware. A unit, or the like, may be configured so as to reside in anaddressable storage medium or to drive one or more processors. Units, orthe like, may also refer to software components, object-orientedsoftware components, class components, task components, processes,functions, attributes, procedures, subroutines, program code segments,drivers, firmware, microcode, circuits, data, databases, datastructures, tables, arrays or variables. A function provided by acomponent and unit may be a combination of smaller components and units,and may be combined with others to compose larger components and units.Components and units may be configured to drive a device or one or moreprocessors in a secure multimedia card.

Prior to the detailed description, terms or definitions necessary tounderstand the disclosure are described. However, these terms should beconstrued in a non-limiting way.

A “base station (BS)” is an entity communicating with a user equipment(UE) and may be referred to as a BS, base transceiver station (BTS),node B (NB), evolved NB (eNB), access point (AP), fifth generation (5G)NB (5GNB), or next generation (gNB).

A “UE” is an entity communicating with a BS and may be referred to as aUE, device, mobile station (MS), mobile equipment (ME), or terminal.

Stored SI Validation

In the 5G system, a UE acquires the system information (SI) acquisitionupon cell selection (e.g., upon power on), cell-reselection, return fromout of coverage, after reconfiguration with sync completion, afterentering the network from another radio access technology (RAT), uponreceiving an indication that the system information has changed, uponreceiving a public warning system (PWS) notification, and/or wheneverthe UE does not have a valid version of a stored SI. In the 5G system,any system information block (SIB) except SIB1 can be configured to becell specific or area specific. The cell specific SIB is applicable onlywithin a cell that provides the SIB while the area specific SIB isapplicable within an area referred to as an SI area, which consists ofone or several cells and is identified by systemInformationAreaID.

When the UE acquires a master information block (MIB) or an SIB1 or a SImessage in a currently camped/serving cell, the UE can store theacquired SI. A version of the SI that the UE stored is no longer valid 3hours after acquisition. The UE may use a valid stored version of the SIexcept MIB and SIB1, e.g., after cell re-selection, upon return from outof coverage or after the reception of SI change indication. A storedversion of the area specific SIB is valid in a public land mobilenetwork (PLMN) if the systeminformationAreaID and the valueTag that areincluded in the SIB1 received from the currently camped/serving cell areidentical to the PLMN identity, systemInformationAreaM and the valueTagassociated with the stored version of that SIB.

The SIB1 acquired from camped/serving cell includesPLMN-IdentityInfoList comprising of multiple PLMNs. In the current 5Gstandard, when the UE stores the SIB(s) acquired from a cell, it is notdefined whether all PLMNs or a specific PLMN in thePLMN-IdentityInfoList in the SIB1 acquired from that cell are associatedwith stored SIBs acquired from that cell.

Embodiment 1

FIG. 1 is a flowchart that shows UE operations for validating stored SIaccording to an embodiment of the disclosure.

Although not shown, when the UE powers on, the UE performs cell searchand selects a cell.

Referring to FIG. 1, the UE acquires (i.e., receives) an SIB1 from thecamped/serving cell at operation 110. The UE receives in the SIB1,PLMN-IdentityInfoList, systemInformationAreaID, valueTag per SIB, SIscheduling information, and/or other information like unified accesscontrol (UAC). The UE stores the received PLMN-IdentityInfoList,systemInformationAreaID, valueTag per SIB, and information per SIBwhether SIB is cell specific or area specific.

The UE receives other required SIB(s) (e.g., SIB2, SIB3, SIB4 and so on)and stores them at operation 120. The UE may receive the other requiredSIB(s) based on the SI scheduling information in the SIB1 or byperforming the SI request.

The UE performs cell reselection based on the information received inSIB2, SIB3 and SIB4, and the UE receives the SIB1 from the camped cellat operation 130.

The UE identifies whether the stored systemInformationAreaID and thesystemInformationAreaID received from the SIB1 are the same at operation140.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same, the UE identifies whether the firstPLMN-identity of the stored PLMN-IdentityInfoList and the firstPLMN-identity of the PLMN-IdentityInfoList received from the SIB1 arethe same at operation 150.

If the first PLMN-identity of the stored PLMN-IdentityInfoList and thefirst PLMN-identity of the PLMN-IdentityInfoList received from the SIB1are the same, for each stored SIB, the UE considers the stored SIBfulfilling following conditions valid and applies them for the campedcell at operation 160: Condition 1: the SIB is system information areaspecific according to the information received from the SIB 1. Condition2: the stored value tag of that SIB is the same as the value tagreceived from the SIB1 for that SIB.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are different, or if the first PLMN-identity ofthe stored PLMN-IdentityInfoList and the first PLMN-identity of thePLMN-IdentityInfoList received from the SIB1 are different, the UEdetermines that the stored SI is not valid in the camped cell, andacquires SIB(s) from the camped cell at operation 170.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot as follows:

1> If stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same and 1> If the first PLMN-identity ofthe stored PLMN-IdentityInfoList and the first PLMN-identity of thePLMN-IdentityInfoList received from the SIB1 are the same, then _(——)2>For each stored SIB, UE considers the stored SIBs fulfilling followingconditions valid and apply it for the camped cell, where _(———)3> TheSIB is system information area specific according to the informationreceived from the SIB1, and _(———)3> The stored value tag for that SIBis the same as the value tag received from the SIB1 for that SIB.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot for area specific SIB as follows:

1> The UE can, _(——)2> for each stored version of an SIB, _(———)3> ifthe stored SIB has an area scope and if the first PLMN- Identityincluded in the PLMN-IdentityInfoList, the systemInformationAreaID andthe valueTag that are included in the SIB1 received from the currentlycamped/serving cell are identical to the first PLMN-Identity in thePLMN-IdentityInfoList of the stored SIB1, the systemInformationAreaIDand the valueTag associated with the stored version of that SIB, then_(——) _(——)4> consider the stored SIB as valid for the cell.

Embodiment 2

FIG. 2 is another flowchart that shows UE operations for validatingstored SI according to an embodiment of the disclosure.

Although not shown, when the UE powers on, the UE performs cell searchand selects a cell.

Referring to FIG. 2, the UE acquires (i.e., receives) an SIB1 from thecamped/serving cell at operation 210. The UE receives in the SIB1,PLMN-IdentityInfoList, systemInformationAreaID, valueTag per SIB, SIscheduling information, and/or other information like UAC. Theinformation element (IE) PLMN-IdentityInfoList includes a list of PLMNidentity information. The SI scheduling information contains informationneeded for acquisition of SI messages. The systemInformationAreaID,valueTag and area scope information may be included in SI schedulinginformation. The valueTag and area scope information is signaled perSIB. An area scope field indicates that a SIB is area specific. If thefield is not present, the SIB is cell specific. A valueTag for a SIB isan identifier for a set of values of parameters of that SIB. Forexample, let's say a SIB has two parameters X and Y. Possible values ofX are Xa, Xb, Xc. Possible values of Y are Ya, Yb, Yc. Cell maybroadcast X:Xa, Y:Yb in this SIB and indicates valueTag for this SIBas 1. Later, cell may update SIB and broadcast X:Xb, Y:Ya in this SIBand indicates valueTag for this SIB as 2. The systemInformationAreaIDindicates the system information area that the cell belongs to. The areascope information indicates whether an SIB is area specific. The UEstores the first PLMN identity in the received PLMN-IdentityInfoList,systemInformationAreaID, valueTag per SIB, and/or information per SIBwhether SIB is cell specific or area specific.

The UE receives other required SIB(s) (e.g., SIB2, SIB3, SIB4 and so on)and stores them at operation 220. The UE may receive other requiredSIB(s) based on the SI scheduling information in the SIB1 or byperforming the SI request based on the SIB.

The UE performs cell reselection based on the information received inSIB2, SIB3 and SIB4, and the UE receives SIB1 from the camped cell atoperation 230.

The UE identifies whether the stored systemInformationAreaID and thesystemInformationAreaID received from the SIB1 are the same at operation240.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same, the UE identifies whether thestored PLMN-identity and the first PLMN-identity of thePLMN-IdentityInfoList received from the SIB1 are the same at operation250.

If the stored PLMN-identity and the first PLMN-identity of thePLMN-IdentityInfoList received from the SIB1 are the same, for each SIBthe UE considers the stored SIBs fulfilling following conditions validand applies them for the camped cell at operation 260: Condition 1: theSIB is system information area specific according to the informationreceived from the SIB1. Condition 2: the stored value tag for that SIBis the same as the value tag received from the SIB1 for that SIB.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are different, or if the stored PLMN-identity andthe first PLMN-identity of the PLMN-IdentityInfoList received from theSIB1 are different, the UE determines that the stored SI is not valid inthe camped cell, and acquires SIB(s) from the camped cell at operation270.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot as follows:

1> If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same, and 1> If the stored PLMN-identityand the first PLMN-identity of the PLMN-IdentityInfoList received fromthe SIB1 are the same, then _(——)2> For each SIB, UE considers thestored SIBs fulfilling following conditions valid and apply them for thecamped cell, where _(———)3> The SIB is system information area specificaccording to the information received from the SIB1, and _(———)3> Thestored value tag for the SIB is the same as the value tag received fromthe SIB1 for that SIB.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot for area specific SIB as follows:

1> The UE can, _(——)2> for each stored version of an SIB, _(———)3> ifthe stored SIB has an area scope and if the first PLMN- Identityincluded in the PLMN-IdentityInfoList, the systemInformationAreaID andthe valueTag that are included in the SIB1 received from the currentlycamped/serving cell are identical to the stored PLMN-Identity (UE storesthe first PLMN identity in the PLMN-IdentityInfoList acquired from SIB1,while storing the acquired SI), the systemInformationAreaID and thevalueTag associated with the stored version of that SIB, then _(——)_(——)4> consider the stored SIB as valid for the cell.

Embodiment 3

FIG. 3 is another flowchart that shows UE operations for validatingstored SI according to an embodiment of the disclosure.

Although not shown, when the UE powers on, the UE performs cell searchand selects a cell.

Referring to FIG. 3, the UE acquires (i.e., receives) the SIB1 from thecamped/serving cell at operation 310. The UE receives in the SIB1,PLMN-IdentityInfoList, systemInformationAreaID, valueTag per SIB, SIscheduling information, and/or other information like UAC. The SIB1includes information indicating which PLMN identity among the multiplePLMN identities in PLMN-IdentityInfoList is associated with SI. The UEstores a PLMN identity from the received PLMN-IdentityInfoList which isassociated with SI in the cell. The UE also storessystemInformationAreaID, valueTag per SIB, and information per SIBwhether SIB is cell specific or area specific.

The UE receives other required SIB(s) (e.g., SIB2, SIB3, SIB4 and so on)and stores them at operation 320. The UE may receive the other requiredSIB(s) based on the SI scheduling information in the SIB1 or byperforming the SI request.

The UE performs cell reselection based on the information received inSIB2, SIB3 and SIB4, and the UE receives SIB1 from the camped cell atoperation 330.

The UE identifies whether the stored systemInformationAreaID and thesystemInformationAreaID received from the SIB1 are the same at operation340.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same, the UE identifies whether thestored PLMN-identity and the PLMN-identity associated with SI in thePLMN-IdentityInfoList received from the SIB1 are the same at operation350.

If the stored PLMN-identity and the PLMN-identity associated with SI inthe PLMN-IdentityInfoList received from the SIB1 are the same, for eachSIB the UE considers the stored SIBs fulfilling following conditionsvalid and applies them for the camped cell at operation 360: Condition1: the SIB is system information area specific according to theinformation received from the SIB 1. Condition 2: the stored value tagfor the SIB is the same as the value tag received from the SIB1 for thatSIB.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are different, or if the stored PLMN-identity andthe PLMN-identity associated with SI in the PLMN-IdentityInfoListreceived from the SIB1 are different, the UE determines that the storedSI is not valid in the camped cell, and acquires SIB(s) from the campedcell at operation 370.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot as follows:

1> If stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same, and 1> If the stored PLMN-identityand the PLMN-identity associated with SI in the PLMN-IdentityInfoListreceived from the SIB1 are the same, then _(——)2> For each SIB, UEconsiders the stored SIBs fulfilling following conditions valid andapply them for the camped cell, where _(———)3> The SIB is systeminformation area specific according to the information received from theSIB1, and _(———)3> The stored value tag of the SIB is the same as thevalue tag received from the SIB1 for that SIB.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot for area specific SIB as follows:

1> The UE can, _(——)2> for each stored version of an SIB, _(———)3> ifthe stored SIB has an area scope and if the PLMN-identity associatedwith SI included in the PLMN-IdentityInfoList, thesystemInformationAreaID and the valueTag that are included in the SIB1received from the currently camped/serving cell are identical to thestored PLMN-Identity, the systemInformationAreaID and the valueTagassociated with the stored version of that SIB, then _(——) _(——)4>consider the stored SIB as valid for the cell.

Embodiment 4

FIG. 4 is another flowchart that shows UE operations for validatingstored SI according to an embodiment of the disclosure

Although not shown, when the UE powers on, the UE performs cell searchand selects a cell.

Referring to FIG. 4, the UE acquires (i.e., receives) the SIB1 from thecamped/serving cell at operation 410. The UE receives in SIB1,PLMN-IdentityInfoList, systemInformationAreaID, valueTag per SIB, SIscheduling information, and/or other information like UAC. For each SIBsupported in the cell, SIB1 includes information indicating which PLMNidentity among the multiple PLMN identities in PLMN-IdentityInfoList isassociated with that SIB. For each SIB, the UE stores a PLMN identityfrom the received PLMN-IdentityInfoList which is associated with SIB inthe cell. The UE also stores systemInformationAreaID, valueTag per SIB,and information per SIB whether SIB is cell specific or area specific.

The UE receives other required SIB(s) (e.g., SIB2, SIB3, SIB4 and so on)and stores them at operation 420. The UE may receive the other requiredSIB(s) based on the SI scheduling information in the SIB1 or byperforming the SI request.

The UE performs cell reselection based on the information received inSIB2, SIB3 and SIB4, and the UE receives SIB1 from the camped cell atoperation 430.

For each SIB, the UE identifies whether the storedsystemInformationAreaID and the systemInformationAreaID received fromthe SIB1 are the same at operation 440.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same, the UE identifies whether thePLMN-identity associated with this SIB in the PLMN-IdentityInfoList ofstored SIB1 and the PLMN-identity associated with this SIB in thePLMN-IdentityInfoList received from the SIB 1 are the same at operation450.

If the PLMN-identity associated with this SIB in thePLMN-IdentityInfoList of stored SIB1 and the PLMN-identity associatedwith this SIB in the PLMN-IdentityInfoList received from the SIB1 arethe same, the UE considers the stored SIB fulfilling followingconditions valid and applies them for the camped cell at operation 460:Condition 1: the SIB is system information area specific according tothe information received from the SIB 1. Condition 2: the stored valuetag is the same as the value tag received from the SIB 1.

If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are different, or if the PLMN-identity associatedwith this SIB in the PLMN-IdentityInfoList of stored SIB1 and thePLMN-identity associated with this SIB in the PLMN-IdentityInfoListreceived from the SIB1 are different, the UE determines that the storedSI is not valid in the camped cell, and acquires SIB(s) from the campedcell at operation 470.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot as follows:

1> If the stored systemInformationAreaID and the systemInformationAreaIDreceived from the SIB1 are the same, and 1> If the PLMN-identityassociated with this SIB in the PLMN- IdentityInfoList of stored SIB1and the PLMN-identity associated with this SIB in thePLMN-IdentityInfoList received from the SIB1 are the same, then _(——)2>For each SIB UE considers the stored SIBs fulfilling followingconditions valid and apply them for the camped cell, where _(———)3> TheSIB is system information area specific according to the informationreceived from the SIB1, and _(———)3> The stored value tag for the SIB isthe same as the value tag received from the SIB1 for that SIB.

In this embodiment of the disclosure, upon cell selection (e.g., uponpower on), cell-reselection, return from out of coverage, afterreconfiguration with sync completion, after entering the network fromanother RAT, upon receiving an indication that the system informationhas changed, upon receiving a PWS notification, and/or upon acquiringSIB1, the UE checks whether the stored system information is valid ornot for area specific SIB as follows:

1> The UE can, _(——)2> for each stored version of a SIB, _(———)3> if thestored SIB has an area scope and if the PLMN-identity associated withthis SIB in the PLMN-IdentityInfoList, the systemInformationAreaID andthe valueTag that are included in the SIB1 received from the currentlycamped/serving cell are identical to the stored PLMN-Identity associatedwith this SIB in the PLMN-IdentityInfoList of stored SIB1, thesystemInformationAreaID and the valueTag associated with the storedversion of that SIB, then _(——) _(——)4> consider the stored SIB as validfor the cell.Beam Failure Configuration Update

In the beamformed system, beam failure recovery (BFR) procedure is usedto recover beam upon beam failure detection. The UE may be configured byradio resource control (RRC) with a BFR procedure which is used forindicating to the serving gNB of a new synchronization signal (SS) block(SSB) or channel state information reference signal (CSI-RS) when beamfailure is detected on the serving SSB(s)/CSI-RS(s). Beam failure isdetected by counting beam failure instance indication.

The RRC configures the parameters in the BeamFailureRecoveryConfig forthe beam failure detection and recovery procedure. The gNB may configurecontention free resources for BFR. The UE operation for beam failuredetection and recovery in 5G system is as follows:

1> If beam failure instance is detected, then _(——)2> the UE starts orrestarts the beamFailureDetectionTimer, _(——)2> increments BFI_COUNTERby 1, and _(——)2> if BFI_COUNTER >= beamFailureInstanceMaxCount, then:_(———)3> initiates a random access (RA) procedure on the special cell(SpCell).

When the RA procedure is initiated on the SpCell:

1> if beamFailureRecoveryConfig is configured, then _(——)2> start thebeamFailureRecoveryTimer, if configured, and _(———)3> apply theparameters powerRampingStep, preambleReceivedTargetPower, andpreambleTransMax configured in beamFailureRecoveryConfig. 1> If the RAprocedure is successfully completed, then _(——)2> stop thebeamFailureRecoveryTimer if configured, and _(———)3> consider the BFRprocedure successfully completed.Scenario 1:

In this scenario, the UE is configured with beam failure detectionconfiguration. The UE is also configured with BFR configuration. Thecontention free RA resources are provided for BFR request. The UEdetects beam failure and initiates RA procedure for BFR. While the RAprocedure for BFR is ongoing, the UE receives RRCReconfigurationincluding updated BFR configuration (contention free RA resources forBFR request are updated). Note that during BFR for primary secondarycell (PSCell), the UE can receive the RRCReconfiguration includingupdated BFR configuration from the primary cell (PCell). In thisscenario, the issue is that the UE uses the contention free BFRresources for RA which are no longer valid.

Scenario 2:

In this scenario, the UE is configured with beam failure detectionconfiguration. The UE is not configured with BFR configuration. The UEdetects beam failure and initiates RA procedure for BFR. While the RAprocedure for BFR is ongoing, the UE receives RRCReconfigurationincluding BFR configuration (contention free RA resources are provided).Note that during BFR for PSCell, the UE can receive theRRCReconfiguration including updated BFR configuration from the PCell.In this scenario, the issue is that the UE uses the contention basedPRACH resources for BFR even when contention free RA resources areavailable.

Embodiment 1

In an embodiment of the disclosure, upon receiving the updated BFRconfiguration while the BFR is ongoing, the UE terminates the ongoing RAprocedure for BFR. The UE re-initiates the RA procedure using theupdated configuration. If the updated BFR configuration for a servingcell is received during an ongoing RA procedure for BFR of that servingcell, the UE terminates the ongoing RA procedure for BFR. The UEre-initiates the RA procedure using the updated configuration.

FIG. 5 shows signaling flow between a UE and a gNB according to anembodiment of the disclosure.

Referring to FIG. 5, the gNB transmits an RRC reconfiguration message tothe UE at operation 510. The RRC reconfiguration message may includebeam failure detection configuration and/or BFR configuration. Forexample, in Scenario 1 described above, the UE is configured with beamfailure detection configuration and BFR configuration. In Scenario 2described above, the UE is configured with beam failure detectionconfiguration, but the UE is not configured with BFR configuration.

If beam failure detection criteria are met at operation 520, the UEinitiates RA procedure for BFR based on the BFR configuration atoperation 530. For example, if beam failure instance indication has beenreceived from lower layers and a counter for beam failure instanceindication BFI COUNTER which is initially set to 0 is greater than orequal to beamFailurelnstanceMaxCount for the beam failure detection, theUE initiates an RA procedure for BFR.

While the RA procedure for BFR is ongoing, if the UE receives an RRCreconfiguration message including updated BFR configuration at operation540, the UE can proceed to operations 550 and 560. In an example, in theupdated BFR configuration, contention free RA resources for BFR requestare updated (Scenario 1), or contention free RA resources are provided(Scenario 2).

If beamFailureRecoveryConfig is reconfigured, the UE terminates theongoing RA procedure for BFR at operation 550, and the UE re-initiatesan RA procedure for BFR using the new configuration at operation 560.The UE may select RA resources for a BFR request based on the newconfiguration, and transmit the BFR request based on the selected RAresources to the gNB.

FIG. 6 is a flowchart that shows UE operations according to anembodiment of the disclosure.

Referring to FIG. 6, upon receiving the RRC reconfiguration messageincluding the BFR configuration at operation 610, the UE checks whetherthe RA procedure is ongoing for BFR or not for the serving cell forwhich BFR configuration is received at operation 620. If the RAprocedure is ongoing for BFR for the serving cell for which BFRconfiguration is received, the UE terminates the ongoing RA procedurefor BFR at operation 630. The UE re-initiates the RA procedure for BFRfor that serving cell using the updated configuration at operation 640.

Embodiment 2

In an embodiment of the disclosure, upon receiving the updated BFRconfiguration while the BFR is ongoing, the UE continues the ongoing RAprocedure for BFR. For the remaining RA procedure (subsequent randomaccess channel (RACH) attempts), the UE uses the updated configuration(RACH resources and parameters). If the updated BFR configuration for aserving cell is received during an ongoing RA procedure for BFR of thatserving cell, the UE continues the ongoing RA procedure for BFR. For theremaining RA procedure (subsequent random access channel (RACH)attempts), the UE uses the updated configuration (RACH resources andparameters).

FIG. 7 shows signaling flow between a UE and a gNB according to anembodiment of the disclosure.

Referring to FIG. 7, the gNB transmits an RRC reconfiguration message tothe UE at operation 710. The UE is configured with beam failuredetection configuration and/or BFR configuration based on the RRCreconfiguration message. If beam failure detection criteria are met atoperation 720, the UE initiates RA procedure for BFR at operation 730.If the UE receives an RRC reconfiguration message including updated BFRconfiguration while the RA procedure for BFR is ongoing at operation740, the UE uses the updated RACH configuration for ongoing RA procedurefor BFR at operation 750. If contention-free RA resources for BFRrequest are updated, the UE (re)-starts the BFR timer at operation 760.

FIG. 8 is another flowchart that shows UE operations according to anembodiment of the disclosure.

Referring to FIG. 8, upon receiving the RRC reconfiguration messageincluding the BFR configuration at operation 810, the UE checks whetherthe RA procedure is ongoing for BFR or not for the serving cell forwhich BFR configuration is received at operation 820. If the RAprocedure is ongoing for BFR for the serving cell for which BFRconfiguration is received, the UE continues the ongoing RA procedure forBFR at operation 830. For the remaining RA procedure (subsequent RACHattempts) for BFR on that serving cell, the UE uses the updatedconfiguration (RACH resources and parameters). If contention-free RAresources for BFR request are updated, the UE (re-)starts the BFR timerat operation 840.

Embodiment 3

In an embodiment of the disclosure, upon receiving the updated BFRconfiguration while the BFR is ongoing, if RACH configuration in updatedBFR configuration is different from the current RACH configuration beingused for BFR, the UE terminates the ongoing RA procedure for BFR, andthe UE re-initiates the RA procedure using the updated configuration.

FIG. 9 shows another signaling flow between a UE and a gNB according toan embodiment of the disclosure.

Referring to FIG. 9, the gNB transmits an RRC reconfiguration message tothe UE at operation 910. The UE is configured with beam failuredetection configuration and/or BFR configuration based on the RRCreconfiguration message. If beam failure detection criteria are met atoperation 920, the UE initiates RA procedure for BFR at operation 930.If the UE receives an RRC reconfiguration message including updated BFRconfiguration while the RA procedure for BFR is ongoing at operation940, the UE terminates the ongoing RA procedure for BFR if RAconfiguration is updated at operation 950, and the UE re-initiates an RAprocedure for BFR using the new configuration at operation 960.

FIG. 10 is another flowchart that shows UE operations according to anembodiment of the disclosure.

Referring to FIG. 10, upon receiving the RRC reconfiguration messageincluding the BFR configuration at operation 1010, the UE checks whetherthe RA procedure is ongoing for BFR or not for the serving cell forwhich BFR configuration is received at operation 1020. If the RAprocedure is ongoing for BFR for the serving cell for which BFRconfiguration is received and if RACH configuration in updated BFRconfiguration is different from the current RACH configuration beingused for BFR configuration, the UE terminates that ongoing RA procedurefor BFR at operation 1030. The UE re-initiates the RA procedure for BFRfor that serving cell using the updated configuration at operation 1040.

FIG. 11 is a block diagram of a terminal according to an embodiment ofthe disclosure.

Referring to FIG. 11, a terminal includes a transceiver 1110, acontroller 1120 and a memory 1130. The controller 1120 may refer to acircuitry, an application-specific integrated circuit (ASIC), or atleast one processor. The transceiver 1110, the controller 1120 and thememory 1130 are configured to perform the operations of the UEillustrated in the figures, e.g. FIGS. 1 to 10, or as otherwisedescribed above. Although the transceiver 1110, the controller 1120 andthe memory 1130 are shown as separate entities, they may be realized asa single entity like a single chip. The transceiver 1110, the controller1120 and the memory 1130 may also be electrically connected to orcoupled with each other.

The transceiver 1110 may transmit and receive signals to and from othernetwork entities, e.g., a base station.

The controller 1120 may control the UE to perform functions according toone of the embodiments described above.

For example, the controller 1120 is configured to acquire a first SIB1,and other system information based on the first SIB1, and store at leastpart of the first SIB1 and the other system information in the memory1130. The controller 1120 is further configured to store information ona PLMN identity and a value tag of the first SIB1 in the memory 1130.The controller 1120 may be further configured to store area scopeinformation indicating whether the first SIB1 is area specific or cellspecific, and a system information area identity of the first SIB1 inthe memory 1130. The controller 1120 is further configured to controlthe transceiver 1110 to receive a second SIB1 from a cell, and determinewhether the stored at least part of the first SIB1 and the other systeminformation are valid for the cell based on whether information on aPLMN identity and a value tag of the second SIB1 are identical to thestored information on the PLMN identity and the stored value tag. Thecontroller 1120 may be further configured to identify that the stored atleast part of the first SIB1 and the other system information are validfor the cell if the stored area scope information indicates that thefirst SIB1 is area specific, and the second SIB1 is area specific, andthe information on the PLMN identity, a system information area identityand the value tag of the second SIB1 are identical to the storedinformation on the PLMN identity, the stored system information areaidentity and the stored value tag.

For example, the controller 1120 is configured to control thetransceiver 1130 to receive, from a base station, first configurationinformation for BFR, and initiate a first RA procedure for BFR based onthe first configuration information if beam failure is detected. Thecontroller 1120 is further configured to terminate the first RAprocedure and initiate a second RA procedure for BFR based on secondconfiguration information if the second configuration information forBFR is received while the first RA procedure is ongoing.

In an embodiment, the operations of the terminal may be implementedusing the memory 1130 storing corresponding program codes. Specifically,the terminal may be equipped with the memory 1130 to store program codesimplementing desired operations. To perform the desired operations, thecontroller 1120 may read and execute the program codes stored in thememory 1130 by using a processor or a central processing unit (CPU).

FIG. 12 is a block diagram of a base station according to an embodimentof the disclosure.

Referring to FIG. 12, a base station includes a transceiver 1210, acontroller 1220 and a memory 1230. The controller 1220 may refer to acircuitry, an application-specific integrated circuit (ASIC), or atleast one processor. The transceiver 1210, the controller 1220 and thememory 1230 are configured to perform the operations of the network(e.g., gNB) illustrated in the figures, e.g. FIGS. 1 to 10, or asotherwise described above. Although the transceiver 1210, the controller1220 and the memory 1230 are shown as separate entities, they may berealized as a single entity like a single chip. The transceiver 1210,the controller 1220 and the memory 1230 may also be electricallyconnected to or coupled with each other.

The transceiver 1210 may transmit and receive signals to and from othernetwork entities, e.g., a terminal. The controller 1220 may control thebase station to perform functions according to one of the embodimentsdescribed above. For example, the controller is configured to controlthe transceiver 1210 to transmit, to a terminal, first configurationinformation for BFR, control the transceiver 1210 to transmit, to theterminal, second configuration information for BFR, and control thetransceiver 1210 to receive, from the terminal, a BFR request. If thesecond configuration is transmitted while the terminal performs an RAprocedure for BFR based on the first configuration, the request is basedon the second configuration. The controller 1220 may refer to acircuitry, an ASIC, or at least one processor. In an embodiment, theoperations of the base station may be implemented using the memory 1230storing corresponding program codes. Specifically, the base station maybe equipped with the memory 1230 to store program codes implementingdesired operations. To perform the desired operations, the controller1220 may read and execute the program codes stored in the memory 1230 byusing a processor or a CPU.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and detail may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method by a terminal for performing a beamfailure detection and recovery procedure, the method comprising:receiving, from a base station, first configuration information for beamfailure recovery (BFR); when beam failure is detected, initiating afirst random access (RA) procedure for BFR based on the firstconfiguration information for BFR; and when second configurationinformation including a new configuration for BFR is received while thefirst RA procedure for BFR is ongoing, terminating the first RAprocedure for BFR and initiating a second RA procedure for BFR based onthe new configuration for BFR.
 2. The method of claim 1, wherein thefirst configuration information for BFR comprises information oncontention-free random access channel (RACH) resources for BFR request.3. The method of claim 1, wherein the second configuration informationfor BFR comprises new information on contention-free random accesschannel (RACH) resources for BFR request.
 4. The method of claim 3,wherein the initiating of the second RA procedure comprises: selectingRA resources for a second BFR request based on the new information; andtransmitting, to the base station, the second BFR request based on theselected RA resources.
 5. The method of claim 1, wherein the beamfailure is detected on a first cell, and wherein the secondconfiguration information for BFR is received from a second cell.
 6. Themethod of claim 1, wherein when second configuration information for BFRis not received while the first RA procedure is ongoing, maintaining thefirst RA procedure.
 7. A method by a base station for performing a beamfailure recovery (BFR) procedure, the method comprising: transmitting,to a terminal, first configuration information for BFR; transmitting, tothe terminal, second configuration information including a newconfiguration for BFR; and receiving, from the terminal, a BFR request,wherein when the second configuration information for BFR is transmittedwhile the terminal performs a first random access (RA) procedure for BFRbased on the first configuration information for BFR, the request isbased on a second RA procedure for BFR using the new configuration forBFR.
 8. The method of claim 7, wherein the second configurationinformation for BFR comprises information on contention-free randomaccess channel (RACH) resources for the BFR request.
 9. The method ofclaim 7, wherein the second configuration information for BFR is used toconfigure the BFR on a first cell, and wherein the second configurationinformation for BFR is received from a second cell.
 10. A terminal in acommunication system, the terminal comprising: a transceiver; and atleast one processor coupled with the transceiver and configured to:control the transceiver to receive, from a base station, firstconfiguration information for beam failure recovery (BFR), when beamfailure is detected, initiate a first random access (RA) procedure forBFR based on the first configuration information for BFR, and whensecond configuration information including a new configuration for BFRis received while the first RA procedure for BFR is ongoing, terminatethe first RA procedure for BFR and initiate a second RA procedure forBFR based on the new configuration for BFR.
 11. The terminal of claim10, wherein the first configuration information for BFR comprisesinformation on contention-free random access channel (RACH) resourcesfor BFR request.
 12. The terminal of claim 10, wherein the secondconfiguration information for BFR comprises new information oncontention-free random access channel (RACH) resources for BFR request.13. The terminal of claim 12, wherein the at least one processor isfurther configured to: select RA resources for a second BFR requestbased on the new information, and control the transceiver to transmit,to the base station, the second BFR request based on the selected RAresources.
 14. The terminal of claim 10, wherein the beam failure isdetected on a first cell, and wherein the second configurationinformation for BFR is received from a second cell.
 15. The terminal ofclaim 10, wherein when second configuration information for BFR is notreceived while the first RA procedure is ongoing, maintaining the firstRA procedure.
 16. A base station in a communication system, the basestation comprising: a transceiver; and at least one processor coupledwith the transceiver and configured to: control the transceiver totransmit, to a terminal, first configuration information for beamfailure recovery (BFR), control the transceiver to transmit, to theterminal, second configuration information including a new configurationfor BFR, and control the transceiver to receive, from the terminal, aBFR request, wherein when the second configuration information for BFRis transmitted while the terminal performs a first random access (RA)procedure for BFR based on the first configuration information for BFR,the request is based on a second RA procedure for BFR using the newconfiguration for BFR.
 17. The base station of claim 16, wherein thesecond configuration information for BFR comprises information oncontention-free random access channel (RACH) resources for the BFRrequest.
 18. The base station of claim 16, wherein the secondconfiguration information for BFR is used to configure the BFR on afirst cell, and wherein the second configuration information for BFR isreceived from a second cell.